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United States Patent |
6,086,307
|
Johanson
|
July 11, 2000
|
Hoppers with directionally applied relative motion to promote solids flow
Abstract
An improvement to a hopper to promote the flow of solid particulate
material includes mounting one or more walls of the hopper for limited
oscillatory motion in a direction parallel to the wall and perpendicular
to the desired flow direction, and then providing an actuator connected to
the remainder of the hopper to impart such motion to the wall. The
relative motion between the moving wall and the particulate material
effectively rotates the friction force to the direction of relative
motion, leaving the friction in the desired flow direction approaching
zero. As a result, downward flow can occur on walls that are only
shallowly inclined. The improvement is applicable to hopper-like
structures in railroad cars and ships, where it facilitates discharge onto
moving conveyors.
Inventors:
|
Johanson; Jerry R. (San Luis Obispo, CA)
|
Assignee:
|
J R Johanson, Inc. (San Luis Obispo, CA)
|
Appl. No.:
|
963527 |
Filed:
|
November 3, 1997 |
Current U.S. Class: |
414/288 |
Intern'l Class: |
B65G 065/40 |
Field of Search: |
414/288,363,375,415,525.7,525.8
|
References Cited
U.S. Patent Documents
833761 | Oct., 1906 | Stevens | 414/525.
|
3747811 | Jul., 1973 | Lewis et al. | 414/375.
|
4068768 | Jan., 1978 | Hicks, Jr. | 414/375.
|
4775284 | Oct., 1988 | Musschoot | 198/550.
|
4999021 | Mar., 1991 | Reissmann | 414/363.
|
Foreign Patent Documents |
1288014 | Jan., 1969 | DE | 414/288.
|
2752406 | May., 1979 | DE | 414/288.
|
1752671 | Aug., 1992 | SU | 414/288.
|
Primary Examiner: Keenan; James W.
Attorney, Agent or Firm: McKown; Daniel C.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. Provisional Patent Application
Ser. No. 60/030,320 filed Nov. 4, 1996 for HOPPERS WITH DIRECTIONALLY
APPLIED RELATIVE MOTION TO PROMOTE SOLIDS FLOW.
Claims
I claim:
1. A hopper that actively promotes the flow of particulate material through
itself, comprising:
a stationary member;
a movable exterior hopper wall having an inwardly-facing surface along
which the particulate material flows downwardly;
means for coupling said movable exterior hopper wall to said stationary
member for limited oscillatory motion in a direction perpendicular to the
direction of flow, said limited oscillatory motion having no component
perpendicular to said movable exterior hopper wall; and,
means connected to said stationary member and to said movable exterior
hopper wall for moving said movable exterior hopper wall in limited
oscillatory motion in said direction.
2. The hopper of claim 1 wherein said movable exterior hopper wall is
conical and has an axis of symmetry, and wherein said means for moving
drives said movable exterior hopper wall in rotational oscillatory motion
about said axis of symmetry.
3. The hopper of claim 1 further comprising a circular upper edge and a
discharge opening that is bounded by two parallel straight edge sections
alternating with semicircular edge sections, whereby said hopper includes
two planar triangular portions having the straight edge sections as bases,
and wherein said movable exterior hopper wall is one of said two planar
triangular portions.
4. The hopper of claim 1 further comprising inclined planar wall portions
that converge downwardly to a discharge opening, and wherein said movable
exterior hopper wall is one of said inclined planar wall portions.
5. The hopper of claim 1 further comprising inclined planar wall portions
that converge downwardly to opposite sides of a discharge slot, and
wherein said movable exterior hopper wall is one of said inclined planar
wall portions.
6. The hopper of claim 1 wherein said means for coupling is a pivot having
an axis perpendicular to said movable exterior hopper wall, and wherein
the limited oscillatory motion consists of rotational oscillatory motion
about said axis.
Description
STATEMENT RE FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO A "MICROFICHE APPENDIX"
Not applicable.
BACKGROUND OF THE INVENTION
Vibration has been used for years to promote flow in hoppers. The most
direct approach is to hit the hopper with a sledge hammer. More
sophisticated vibration techniques include: electromagnetic, air driven
and motor drivers with eccentric weights. These vibrators applied directly
to bins are sometimes effective in dislodging caked solids. Improvements
have been made over the years by applying the vibrators to internal walls
of the bins, or by suspending the entire hopper on elastic supports so
that the vibration does not activate the entire structure. Most of the
applied vibration is dissipated in unnecessary movement of the structure
or of the solids stored within the hopper. This often causes structural
damage and overcompaction of the bulk solids.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention, discharge flow of solid
particulate material from a hopper is promoted and enhanced by producing a
relative motion between the particulate material and the wall along which
the material is to flow. The relative motion is perpendicular to the
desired direction of flow and parallel to the surface of the wall. This
causes the frictional force between the material and the wall to become
oriented approximately perpendicular to the desired direction of flow,
with the result that friction in the direction of flow is practically
zero.
In a preferred embodiment, the wall is mounted to a stationary portion of
the hopper for limited motion in a direction parallel to its surface and
perpendicular to the desired direction of flow. An actuator is connected
to the stationary portion of the hopper and it acts upon the wall to
impart the desired reciprocating motion to the wall.
This relative motion does not change the magnitude of the friction force,
which remains constant and equal to the forces perpendicular to the wall
times the coefficient of friction. However, the direction of the friction
force always opposes the motion. In accordance with the present invention
the speed of movement of the wall in its reciprocating motion is much
greater than the speed of the downward flow of the particles along the
wall, and therefore the direction of the friction force is approximately
horizontal, and the component of the friction force in the direction of
flow is approximately zero. This permits downward flow to result even when
the wall is inclined at unprecedented shallow angles with respect to the
horizontal.
The oscillatory motion of the wall in the present invention is very
effective in breaking arches that otherwise tend to form in the material,
thereby permitting the particles to flow through smaller outlets than
would otherwise be possible. An additional advantage of the present
invention is that motion of the wall tends to break any adhesion between
the particles and the wall.
The novel features which are believed to be characteristic of the
invention, both as to organization and method of operation, together with
further objects and advantages thereof, will be better understood from the
following description considered in connection with the accompanying
drawings in which several preferred embodiments of the invention are
illustrated by way of example. It is to be expressly understood, however,
that the drawings are for the purpose of illustration and description only
and are not intended as a definition of the limits of the invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
FIG. 1, including FIGS. 1a, 1b, 1c and 1d, shows the application of the
present invention to a chisel-shaped hopper;
FIG. 1a is a top plan view of a hopper to which the present invention has
been applied;
FIG. 1b is a side elevational view in cross section of the hopper of FIG.
1a in the direction 2--2 indicated in FIG. 1a;
FIG. 1c is an end elevational view in cross section of the hopper of FIG.
1a in the direction 1--1 indicated in FIG. 1a;
FIG. 1d is a diagram showing an end view of the dual actuator of FIGS. 1b
and 1c;
FIG. 2, including FIGS. 2a, 2b, 2c and 2d, shows the application of the
present invention to a transition hopper;
FIG. 2a is a top plan view of the transitional hopper to which the present
invention has been applied;
FIG. 2b is a side elevational view of the hopper of FIG. 2a;
FIG. 2c is an end elevational view of the hopper of FIG. 2a;
FIG. 2d is a perspective view of the hopper of FIG. 2a;
FIG. 3, including FIGS. 3a, 3b, 3c and 3d, show the application of the
present invention to a self-unloading ship;
FIG. 3a is a fractional top plan view of a portion of a ship in which the
present invention has been installed;
FIG. 3b is a fractional front elevational view in the direction 3--3
indicated in FIG. 3a;
FIG. 3c is a fractional oblique view of an oscillating corner plate shown
in FIG. 3b;
FIG. 3d is an end view in the direction 4--4 indicated in FIG. 3c;
FIG. 4, including FIGS. 4a, 4b, 4c and 4d, show the application of the
present invention to a multi-sided hopper;
FIG. 4a is a top plan view showing a multi-sided hopper in which the
present invention has been installed;
FIG. 4b is a side elevational view of the hopper of FIG. 4a;
FIG. 4c is a perspective view of the hopper of FIG. 4a;
FIG. 4d is a fractional oblique view of the hopper in the direction 5--5
indicated in FIG. 4b;
FIG. 5, including FIGS. 5a, 5b and 5c, show the application of the present
invention to a section of a conical hopper;
FIG. 5a is a top plan view of a conical hopper in which the present
invention has been installed;
FIG. 5b is a side elevational view of the conical hopper of FIG. 5a;
FIG. 5c is a perspective view of the conical hopper of FIG. 5a;
FIG. 6, including FIGS. 6a, 6b and 6c, show the application of the present
invention to a hopper having corner plates;
FIG. 6a is a top plan view of a hopper having corner plates in which the
present invention has been installed; and,
FIG. 6b is a perspective view of the hopper of FIG. 6a.
DETAILED DESCRIPTION OF THE INVENTION
The simplest form of the invention is a section of flat side wall of a bin
or hopper that is suspended in a way that it can be oscillated
horizontally back and forth. This reduces the frictional component in the
direction of solids flow. This simplest form is shown in FIGS. 1a, 1b, 1c,
and 1d as applied to a one-dimensionally converging chisel-shaped hopper
1. The convergence is caused by two inclined pates 2 intersecting the
vertical cylinder 3. The outer cylinder 4 forms the supporting structure.
The two oscillating side plates 2 provide a one-dimensional convergence to
a slot opening 5 equal in length to the diameter of the cylinder 4. A
cylindrical insert 3 provides cover for the sloping plate edges and the
cavity for the oscillation to occur. A horizontal rod 6 provides a low
friction support for the oscillating walls. The oscillation is achieved by
a cam 7 on the shaft 8 of the screw feeder 9 below the one-dimensional
outlet. The screw 10 is equipped with a varying pitch to provide flow
along the entire slot length. The oscillation occurs only as the screw
turns. This avoids any overcompaction tendency by insuring that the
oscillation does not occur unless the solids are removed from the hopper
outlet. The turning screw activates the linkages 12 that pivot on pin 13
on stationary arm 15 and that are connected to the oscillator rod 6 by pin
14.
The disclosed invention remedies many of the pitfalls of the prior art of
vibration or motion application to bins and hoppers. This invention takes
advantage of gravitational forces to induce solids flow by applying a
relative oscillatory motion between the solids and the hopper wall,
perpendicular to the desired direction of solids flow along the walls.
This reduces the surface frictional component in the direction of solids
flow at sloping walls of the storage hopper. This "slick" low friction
wall promotes flow along the wall and causes increased downward pressure
on solids to break cohesive arches.
For this oscillatory motion to be successful, the relative motion between
the solids and the wall must occur relative to the plane of the hopper and
solids interface without pushing inward. This must be done because this
inward push tends to overcompact the solids. The motion in the plane of
the bin wall must be essentially horizontal and essentially perpendicular
to the solids downward direction. This relative motion does not change the
friction force magnitude, which remains constant and equal to the force
perpendicular to the wall times the friction coefficient. The motion
simply rotates the friction force to the direction of relative motion
between the wall and the solids. When the relative horizontal motion is
large with respect to the solids downward motion, the shear force
direction is essentially horizontal, thus creating a very small
(essentially zero) upward component of friction force acting on the
solids. The solids then react as if the friction coefficient has
approached zero. As a result, downward flow can occur on very shallowly
inclined walls. In addition, the unsupported downward force of gravity is
much more effective in breaking bridges and the solids flow through
smaller outlets than without this directionally applied relative motion.
Also, adhesion between the solids and the wall is broken.
Another application is a transition hopper configuration that provides a
rounded end slot shown in FIGS. 2a, 2b, 2c and 2d. The end walls [6] 26
are usually very steep or even slightly expanding in the downward
direction. An alternate wall suspension and activation is indicated in
this application. The triangularly shaped plate 21 is primarily supported
by a bracket 23 welded to the upper flange 24 and an antifriction pivot 22
near the top apex of the oscillating plate. The activation is achieved by
a double acting short stroke air cylinder 27 mounted on the bottom hopper
flange 25 and acting on support protrusion 28 connected to the oscillating
plate 21. Intermediate antifriction supports coated with low friction
bearing material such as nylon or with roller supports can be added as
required structurally. As shown, flange 25 provides the outward support
and guide for the oscillatory plates 21. The motion is essentially
perpendicular to the direction of solids flow, especially when the
magnitude of the stroke is very limited. In general, only a few
millimeters movement is required to achieve the advantages of this
invention. This application is further enhanced when the end walls 26 are
slightly diverging downward since this further reduces support of the
solids in the hopper.
A third application is shown in FIGS. 3a, 3b, 3c and 3d. In this case,
two-dimensional convergence is required to feed bulk solids from a
self-unloading ship hold 31 onto a conveyor 32 below. In this case, the
hopper sides 33 must be shallowly inclined to maximize cargo space and to
keep the cargo as low in the hold as possible. In addition, the possible
structural damage from typical applied vibration may endanger the ships
hull 34 and cause leaks or structural failure. The directionally applied
relative motion with its oscillatory action eliminates these problems. The
figure shows both a modified portion of the ship 46 and unmodified portion
47. Only the corner filler plates 35 are oscillated around an upper pivot
point 36. The oscillating plate is supported by the cross beam 37 and
activated by the double acting cylinder 38 at the bottom. The cylinder
acts against protrusions 43 from the oscillating plate 35. This minimizes
the force and requires only one antifriction surface location. The pivot
support 39 located near the top allows for the smallest force for
activation at the more critical hopper outlet location. The oscillating
corner plates 35 provide the low effective friction in the most critical
regions. The plates are sealed against significant solids intrusion under
them by a flexible strip 39 attached to the underside of the oscillating
plate 35. This attachment to the oscillating plate has the advantage of
scraping the stationary plates 33 and 40 and thereby loosening solids
adhered to the stationary plates, thus aiding flow on these stationary
plates. The upper edge of the oscillating plates are protected by an
angular-shaped cover 41 that prevents solids intrusion behind the
oscillating plates. At a vertical bulkhead 45 the closure can be effected
by either the flexible strip 39 or a cover plate 42 that is essentially
half of the angular cover 41. With some materials the oscillating plates
will work satisfactorily without the cover angles or the flexible strips.
The fourth application, shown in FIGS. 4a, 4b, 4c and 4d, is a series of
oscillating flat plates 51 connected to form a converging hopper. The
example shown is a symmetric octangular configuration, although symmetric
or nonsymmetric configurations of three or more sides are also viable
applications. The plates 51 are shown oscillating on a single support
guide 52 although multiple guides can be used if they are required for
additional structural support. The material seal between oscillating
plates 51 is accomplished by a single flexible strip 62 bearing against
adjacent oscillating plates 51. The strip is secured by bolts 63 to the
support 56. The top seal is accomplished by a protruding the lower edge of
the upper stationary hopper 60 below and within the upper edges of the
oscillating plates 51 (a cone-shaped hopper 60 is used in the example
shown). This upper stationary hopper 60 has the advantage of relieving
loads on the oscillating plates 51 thereby reducing both structural
support and oscillatory force requirements. Flow in this upper region is
usually not critical so that a stationary hopper is completely
satisfactory. This is especially true if the ratio of bottom cone 60
diameter to top cylinder 61 diameter is 0.7 or greater. The oscillation is
achieved by either a reciprocating pneumatic or hydraulically driven
piston, or a linear motion vibrator 54 attached from the support rods 52
or the major support beams 56 and acting against the plate supports 53.
The lower solids seal is achieved simply by extending the oscillating
plates 51 to below the lower support ring 55.
By varying the amount of oscillation (either frequency or amplitude or
both) to the oscillating plates, the relative solids velocity of the
center and outside can be varied. The control of the flow pattern allows
the hopper to serve as an adjustable gravity flow blender. The blending
can be enhanced by varying the oscillation around the periphery of the
hopper thus causing a variation in flow from one side to the other.
The next slightly more complicated application is shown in FIGS. 5a, 5b,
and 5c, wherein motion is applied to a conical hopper section 71. In this
case, the supports 72 should be arranged so that the movement is around
the axis of symmetry 73 of the conical section 71.
The curved support rods 72 are connected to the supports 74 that are in
turn connected to the lower flange 75 and upper flange 76. In this
embodiment the oscillation is achieved by attaching the actuator 77 to the
hopper antifriction support bearing 78 and allowing the actuator 77 to act
against the two protruding supports 79 and 80 attached to the support rod
72. The additional support required to stabilize the conical section 71 is
achieved by allowing the conical section 71 to rest against either the
lower flange 75 or the upper flange 76. This support could be replaced by
rollers with axes parallel to the conical surface and attached to flanges
75 or 76 if further friction reduction is desired. The same solids seal
arrangement as shown in FIG. 4 is used in FIG. 5. Similarly this FIG. 5
configuration can be used to modulate the flow pattern in the hopper. The
same concept of oscillation can be used for circular cones with
nonvertical axes.
Another application is a retrofit of a pyramid-shaped hopper shown in FIGS.
6a and 6b. The corner formed by the flat plates 82 are covered and
activated by plates 81. These activated plates 81 are supported by a
corner mounting that provides a support pivot 84 near the top of the
plate. The activation and support is achieved by the rod 83 attached to
plate 81 and protruding from the corners of plates 82 at the bottom.
Activation can be achieved simply by striking rod 83 with a hammer first
on one end then the other. This manual activation eliminates the need for
a linear actuator and allows the operator to strike the hopper without
effectively damaging the structure. Note that in general there will be a
vertical section on the hopper and the plate 81 will extend into the
corner above the hopper and seal solids from getting behind the plate 81.
This embodiment can be effective with or without the flexible seals shown
in FIG. 3.
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